Air relay



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BY am/42] June 10, 1958 Filed Aug. 15, 1956 that is transmitted to the receiver.

United States Patent AIR RELAY Barton Jones, Los Angeles, Calif.

Application August 13, 1956, Serial No. 603,676

Claims. (Cl. 137-620) This invent-ion relates to improvements in air relays such as are used in pneumatic transmitters. This application is a continuation-in-part of my copending application Serial No. 348,232, filed April 13, 1953, now abandoned, and like that application, part of the present application may be regarded as a division of the subject matter disclosed in my copending application Serial No.

326,119 filed December 15, 1952, entitled Air Transmitter now Patent No. 2,718,896.

A primary object of the invention is to provide an air relay wherein compressed air that is delivered from a suitable source of supply has its pressure reduced and regulated by a variable pilot pressure. This compressed air that has its pressure thus reduced and regulated, is delivered through an outlet from the relay to a receiver.

Heretofore,-air relays have been designed wherein air pressure from a suitable supply source has been regulated by a relay valve and then transmitted to a receiver. In many of such constructions the relay valve has been actuated by a pressure responsive device, such as a diaphragm or bellows wherein one side of the diaphragm is subjected to the pressure that is transmitted to the receiver and the other side was subjected to pilot pressure. In such air relays where there was no constant bleed or loss of compressed air to atmosphere the pressure that was transmitted to the receiver was always a direct function of the pilot pressure or bore a definite relationship thereto. In other constructions of air relays heretofore designed where the transmitted pressure was not a direct function of the pilot pressure but the pilot pressure was merely an exciting or triggering pressure, there has always been a constant bleed or escape of compressed air during normal operation.

Another object of the present invention is to provide an air relay wherein the relay valve is actuated by two opposed bellows or pressure responsive means and wherein both bellows are externally subjected to the pressure In this manner, the two bellows or pressure responsive devicesmay be regarded as balanced. The pilot pressure which is conducted to the interior of one of the bellows functions merely as an unbalancing pressure or triggering pressure so that the pressure that is transmitted to the receiver is not a direct function of the pilot pressure. At the same time there is no constant bleed or loss of compressed air to atmosphere and on the contrary escape of air pressure to atmosphere takes place only when occasion requires that the pressure which is transmitted to the receiver be reduced. Inthis manner objections to having the transmitted pressure remain always a direct function of the pilot pressure are avoided and the unnecessary loss of compressed airoccasioned by a constant bleed is likewise avoided. Consequently, a highly efiicient air relay is capable of being constructed which utilizes a pilot pressure bearing no direct relationship to the transmitted pressure and the pilotpressure may be of relatively small magnitude over all varying conditions.

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Another object of the present invention is to provide a construction which is so designed that with very little change the relay may be employed to increase the transmitted pressure when an increase in pilot pressure occurs and decrease the transmitted pressure when a decrease in pilot pressure occurs. Or, in the alternative, the transmitted pressure may be caused to decrease when an increase in the pilot pressure occurs, or conversely, to increase when a decrease in pilot pressure occurs.

With the foregoing and other objects in view, which will be made manifest in the following detailed description and specifically pointed out in the appended claims, reference is had to the accompanying drawings for an illustrative embodiment of the invention, wherein:

Figure 1 is a vertical section through the relay in that position wherein the pressure supplied through the outlet to the receiver is being reduced occasioned by a reduction in pilot pressure and causing the transmitted pressure to be reduced;

Fig. 2 is a view similar to Fig. 1, but illustrating the relay inthat position wherein the pressure through the outlet to the receiver is being increased in accordance with an increase in pilot pressure;

Fig. 3 is a vertical section through an alternative form of relay which is employed when it is desired that the transmitted pressure decrease with a rise in pilot pres sure, and showing the relay in that position wherein the transmitted pressure is being decreased due to a reduction in pilot pressure; and

Fig. 4 is a similar view of the same relay shown in Fig. 3 but illustrating the relay in that position wherein the transmitted pressure is being increased due to a decrease in pilot pressure.

Referring to the accompanying drawing wherein similar reference characters designate similar parts throughout, the air relay embodying the present invention comprises a suitable housing or casing generally indicated at 10. In this housing there is an air inlet 11 through which compressed air from any suitable source is supplied. Most of the air thus supplied is delivered to a valve chamber 12 in which a portion of a relay valve is disposed. The remainder of the air is delivered through passages 13 and through a restrictor 14 to a pilot (not shown), but which is connected to the passage .15. It is the pres-. sure that exists in the passage 15 that controls or governs the action of the relay and insofar as the present invention is concerned, it is immaterial whether the air pressure in the passage 15 is supplied from the inlet 11 through the restrictor 14 or whether it is supplied from some other source. Usually, however, air pressure available from the inlet 11 is utilized to supply the pilot pressure. It is likewise immaterial insofar as the present invention is concerned What the details of construction of the pilot may be that controls or affects or modifies the pilot pressure in the passage 15. The pilot may be of the type disclosed in my copending application or it may be of any other preferred or conventional type.

Within the housing or casing 10 there is a chamber 16 which receives air from the inlet 11 when the relay valve is in the position shown in Fig. 2. Air pressure in the chamber 16 is transmitted through the outlet 17 to the receiver in accordance with the magnitude of the pilot pressure in the passage 15. The chamber 16 may have its top closed by a suitable cap or as disclosed in my copending application the chamber 16 may be closed by a structure embodying the pilot so that the pressure that exists in the chamber 16 may have an influential or modifying effect on the pilot. The chamber 16 is divided by a partition 18 which has a plurality of spaced apertures or passages 19 formed therein so that the partition, in efiect, is in the nature of a spider extending across the chamber and maintaining the upper and lower portions of the chamber in constant communication with each other. In the partition between the passages 19 there is a radial bore 20 which serves to transmit pilot pressure existing in the passage 15 to the space 21 between two concentric bellows 22 and 23. These bellows have their upper ends rigidly secured to the partition 18. Their lower end are connected together and to the lower end of a connecting stem 24-. On the upper side of the partition 18 there is a similar pair of concentric bellows 25 and 26. These bellows have their lower ends rigidly secured to the partition 18 and their upper ends connected together and to the upper end of the stem 24. The bellows 22 and 25 are of the same size so as to have the same effective area and the same is true of the inner bellows 23 and 26. The connecting stem 24 which rigidly connects the outer or floating ends of the four bellows is made up of two parts mutually connected together so as to be rigid with each other such as by a threaded connection 27.

In the lower of these parts there is a passage 28 in which there is a valve seat 29 engageable by a closure 30 of a relay valve. The passage 28 is in communication with an outlet 31 in the form of a radial bore in the partition 18 that releases air pressure from the chamber 16 to atmosphere when the closure 30 is unseated or in the position shown in Fig. l. A small passage 32 communicates with the bore 31 and with the space 33 between the upper bellows 25 and 26 so that the pressure existing in the space 33 is normally atmospheric pressure or equal to whatever pressure may exist in the bore 31.

The closure as is on a stem 34 that extends downwardly through a valve seat 35 and into the valve chamber 12. The valve seat 35 is on a threaded cap 36 and is of such a diameter that the closure 30 is capable of passing therethrough in the course of assembling or disassembling the relay. On the other end of the stem there is a valve closure adapted to seat on the seat 35 and which is held in adjusted position thereon by means of an acorn nut 37 that is threaded onto the bottom of the stem. A coil compression spring 38 is seated on the nut 37 and is compressed between the nut and a cap 39. V

The operation of the above-described construction is substantially as follows:

Air is supplied to the device through the inlet 11 under suitable pressure and when the valve closure 40 is unseated, as shown in Fig. 2, this pressure is conducted to the chamber 16 and thence to the outlet 17 leading to the receiver. The pressure existing in the chamber 16 is equally effective on the upper bellows 25 and 26 and the lower bellows 22 and .23 so that, in effect, these sets of bellows are balanced insofar as the pressure in the chamber 16 is concerned. The bellows are unbalanced by the pilot pressure, in the passage 115 which is conducted to the space 21 but as this pressure is merely an unbalancing pressure its actual value may be but a very small fraction of the pressure existing in the chamber 16. When the pilot pressure in the passage 15 is caused to increase by the pilot this increased pressure that is transmitted to the space 21 causes the lower bellows 22 and 23 to expand downwardly and the upper bellows 25 and 26 to be contracted downwardly so that the closure 30 is engaged and the closure to is unseated, allowing additional air pressure from the inlet 11 to be admitted to the chamber 16 and thence to the outlet 17. Conversely, if the pilot governing the pilot pressure causes the pilot pressure to decrease, the fall in pilot pressure in the chamber 21 allows the lower bellows 22 and 23 to be contracted upwardly, forcing the upper bellows 25 and 2-6 to be expanded upwardly. This upward movement allows the closure 40 to seat, closing oil the supply of pressure from the inlet 11 and if the upward movement of the bellows continues closure 30 will be unseated, allowing some pressure in the chamber 16 to 4 escape through the passage 28 and the passage 31 to atmosphere. This release of pressure in chamber 16 is effective to reduce the pressure transmitted through the outlet 17 to the receiver.

With the construction as disclosed herein, it will be appreciated that increases in pilot pressure are effective to increase the pressure transmitted to the receiver and conversely, decreases in pilot pressure are effective to release pressure in chamber 16 to atmosphere and conrelay valve.

sequently reduce pressure transmitted to the receiver. However, although the pilot pressure directly regulates the pressure transmitted to the receiver, the pilot pressure need have a value that is only a small fraction of the pressure transmitted to the receiver. Furthermore, the difference in the pilot pressure required to unbalance the bellows to open the inlet 11 or to open the outlet 31 may be very small. Consequently, the pilot pressure, although variable, is actually nearly constant under all conditions. Release of pilot pressure by the pilot will consequently be substantially the same when the pressure transmitted to the receiver is high as when it is low.

Another feature of the construction resides in the fact that there is no constant bleed or escape of air from the In other words, air is released through the outlet 31 only when it is desired to reduce the pressure in the chamber 16 which is transmitted to the receiver. Under all other conditions air is retained confined within the chamber 16 and the outlet 17 leading to the receiver.

In the construction shown in Figs. 3 and 4, the construction is substantially the same as that previously described. However, in this form of construction the transmitted pressure rises with the fall of pilot pressure and falls with a rise in pilot pressure. In this form of construction the bore or passage 20, instead of being connected to the chamber 21 between the outer and inner bellows 22 and 23, is connected to the chamber 33 between the outer and inner bellows 25 and 26. Similarly, the vent passage 31 and its port 32 are connected to the chamber 21 between the outer and inner bellows 22 and 23.

In-all other respects the constructions shown in Figs. 3 and 4 is the same. In this form of construction if pilot pressure transmitted to the chamber .33 increases the upper bellows 25 and 26 will be expanded thereby lifting the connecting means between the opposed pairs of bellows and causing seat 29 to be lifted and to recede from the valve closure 30. The air that is admitted to the interior of the housing from the inlet 11 will, to some extent, be allowed to escape past the valve closure 30 and into the vent passage 31. The pressure that is transmitted through the outlet 17 is consequently of a reduced magnitude in response to an increase in pilot pressure. Conversely, as shown in Fig. 4, if the pilot pressure is reduced allowing the upper bellows 25 and 26, due to their springiness or inherent resiliency, to collapse, the valve seat 29 will be caused to descend against the closure 30 closing the outlet to the vent passage 31 and causing the valve closure 40 in the inlet to be unseated from its seat 35. The admission of compressed air from the inlet 11 to the housing and its release through the outlet 17 without permitting any of the air to escape through the vent passage 31 causes the transmitted pressure that is transmitted through outlet 17 to increase in response to a decrease in pilot pressure.

It will be appreciated from the above-described constructions that the device shown in Figs. 3 and 4 is very similar in construction to the device shown in Figs. 1 and 2, and can be accomplished by merely reversing the position of the spider with respect to the upper and lower seats of opposed bellows. In this manner, the same design of relay may be employed to transmit an increase of pressure in response to increase of pilot pressure or to fill converse requirements wherein the transmitted pressure is to decrease in response to an increase in pilot pressure.

It will, therefore, be appreciated that with the improved relay the relay valve is operableby a balanced pair of bellows or pressure-responsive device, and that these remain in balanced condition regardless of the magnitude of the pressure transmitted to the receiver. Being balanced only a slight amount of pilot pressure is required to unbalance them in accordance with the requirements of the pilot, and as the unbalancing can be accomplished by a relatively small pressure, the pilot pressure may at all times remain of relatively low magnitude.

It will be observed that in the construction shown in Figs. 1 and 2 that the internal bellows 26 is at all times exposed both internally and externally to atmospheric pressure. Atmospheric pressure to the external side of bellows 26 is available through passages 31 and 32. Atmospheric pressure to the interior of bellows 26 is accessiblethrough passage 31 and the clearance around stem 24. Consequently, bellows 26 is pneumatically unnecessary and may be omitted unless its presence is desirable to balance or counteract the inherent resiliency of bellows 23. In a similar manner in the construction shown in Figs. 3 and 4, bellows 23 is at all times exposed both internally and externally to atmospheric pressure and is pneumatically ineffective. This bellows in this form of the construction can likewise be omitted unless its presence is desirable for the purpose ofbalancing the inherent resiliency of bellows 26.

Various changes may be made in the details of construction without departing from the spirit and scope of the invention as defined in the appended claims.

I claim:

1. An air relay comprising a housing, an air inlet for admitting compressed air to the housing, a valve closure and seat therefor in the air inlet normally urged to close the inlet, a spider in the housing, bellows mounted on opposite sides of the spider and cooperating therewith to define chambers which are isolated from each other, connecting means rigidly connecting the outer ends of the bellows through the spider to cause them to move in unison, means venting one of the chambers to atmosphere externally of the housing, a passage having a valve seat therein in the connecting means and vented to atmosphere externally of the housing, a valve closure adapted to seat upon said seat, an outlet for transmitted air leading from the housing, means for admitting pilot pressure to the other of said chambers, and means connecting the valve closure in the connecting means to the valve closure in the air inlet whereby when pilot pressure varies the valve closure in the connecting means may seat upon the seat in the connecting means closing said passage against venting to atmosphere and opening the valve in the air inlet, thus altering transmitted pressure in response to variations in pilot pressure.

2. An air relay comprising a housing, an air inlet for admitting compressed air to the housing, a valve in the air inlet normally urged to close the inlet, a spider in the housing, bellows mounted on opposite sides of the spider and cooperating therewith to define chambers which are isolated from each other, connecting means rigidly connecting the outer ends of the bellows through the spider to cause them to move in unison, means venting one of the chambers to atmosphere externally of the housing, a passage having a valve seat therein in the connecting means and vented to atmosphere externally of the housing, a valve closure adapted to seat upon said seat, an outlet for transmitted air leading from the housing, means for admitting pilot pressure to the other of said chambers, and means connecting the valve closure to the valve in the air inlet whereby when pilot pressure increases the valve closure will seat upon the seat in the passage in the connecting means closing said passage against venting to atmosphere and opening the valve in the air inlet thus increasing the transmitted pressure, and

will close and the closure will unseat thus venting the housing to atmosphere and causing the transmitted pressureto decrease.

3. An air-relay comprising a housing, an air inlet for admitting compressed air that is to be transmitted to the housing, a valve in the air inlet normally urged to close the inlet, a spider in the housing, a pair of concentric bellows mounted on one side of the spider and cooperating therewith to define a chamber between the bellows, a pair of concentric bellows mounted on the other side of the spider and cooperating therewith to define a chamber between the bellows isolated from the first mentioned chamber, the first mentioned chamber being vented through the spider to atmosphere externally of the bellows, connecting means rigidly connecting the outer ends of the bellows through the spider to cause the ends of the bellows to move in unison, a passage in the connecting means leading through the spider to atmosphere externally of the housing, a valve seat in said passage, a valve closure adapted to seat upon said valve seat, means for admitting pilot pressure to the second mentioned chamber, an outlet for transmitted air leading from the housing and means connecting the valve closure to the valve in the air inlet whereby as pilot pressure increases the valve closure will seat upon the seat in the passage in the connecting means closing said passage against venting to atmosphere and opening the valve in the air inlet thus increasing the transmitted pressure when pilot pressure decreases the valve in the air inlet will close and the closure will unseat thus venting the housing to atmosphere and causing the transmitted pressure to decrease.

4. An air relay comprising a housing, an air inlet for admitting compressed air to the housing, a valve in the air inlet normally urged to close the inlet, a spider in the housing, bellows mounted on opposite sides of the spider and cooperating therewith to define chambers which are isolated from each other, connecting means rigidly connecting the outer ends of the bellows through the spider to cause them to move in unison, means venting one of the chambers to atmosphere externally of the housing, a passage having a valve seat therein in the connecting means and vented to atmosphere externally of the housing, a valve closure adapted to seat upon said seat, an outlet for transmitted air leading from the housing, means for admitting pilot pressure to the other of said chambers, and means connecting the valve closure to the valve in the air inlet whereby when pilot pressure decreases the valve closure will seat upon the seat in the passage in the connecting means closing said passage against venting to atmosphere and opening the valve in the air inlet thus increasing the transmitted pressure, and when pilot pressure increases the valve in the air inlet will close and the closure will unseat thus venting the housing to atmosphere and causing the transmitted pressure to decrease.

5. An air relay comprising a housing, an air inlet for admitting compressed air that is to be transmitted to the housing, a valve in the air inlet normally urged to close the inlet, a spider in the housing, a pair of concentric bellows mounted on one side of the spider and cooperating therewith to define a chamber between the bellows, a pair of concentric bellows mounted on the other side of the spider and cooperating therewith to define a chamber between the bellows isolated from the first men tioned chamber, the first mentioned chamber being vented through the spider to atmosphere externally of the bellows, connecting means rigidly connecting the outer ends of the bellows through the spider to cause the ends of the bellows to move in unison, a passage in the connecting means leading through the spider to atmosphere externally of the housing, a valve seat in said passage, a

valve closure adapted to seat upon said valve seat, means;

for admitting pilot pressure to the second mentioned chamber, an outlet for transmitted air leading from the when pilot pressure decreases the valve in the air inlet housing and means connecting the valve closure to the valve in the air inlet whereby as pilot pressure decreases Refer-mess Cited in the file of this patent the valve closure will seat upon the seat inihe passage 1 UNTTED STATES PATENTS in the eonnecting means closing said passage against vent-' 461 Bilyeu 7 Oct 8 1948 ing to atmosphere and opening the valve in-the air inlet oor'e 1950 thus increasing the transmitted pressure when pilot pres- 356 'Moore June 1951 sure increases the valvein the air inlet will close and the Jehnson 1952 closure will unseat thus venting the housing to atmosphere 2,659,381 y's'eljos No 17, 1953 and causing the transmitted pressure to decrease. 2,675,819 Eckman APR 20, 5 

